CVE-2026-63875
In the Linux kernel, the following vulnerability has been resolved:
arm64: tlb: Flush walk cache when unsharing PMD tables
When huge_pmd_unshare() is called to unshare a PMD table, the tlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true but the aarch64 tlb_flush() only checked tlb->freed_tables to determine whether to use TLBF_NONE (vae1is, invalidates walk cache) or TLBF_NOWALKCACHE (vale1is, leaf-only).
This caused the stale PMD page table entry to remain in the walk cache after unshare, potentially leading to incorrect page table walks.
Fix by including unshared_tables in the check, so that when unsharing tables, TLBF_NONE is used and the walk cache is properly invalidated.
Leer descripción completaMostrar menos
Here is the detailed distinction between vae1is and vale1is:
| Instruction Combination | Actual Invalidation Scope | | ------------------------ | --------------------------------------------------| | `VAE1IS` + TTL=`0` | All entries at all levels (full invalidation) | | `VAE1IS` + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2 | | `VALE1IS` + TTL=`0` | Leaf entries at all levels (non-leaf not cleared) | | `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only |
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.18%
- Percentil entre todas las CVEs puntuadas: 7
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1005Data from Local Systemcollection75 % - Impacto secundario
T1499.004Application or System Exploitationimpact60 %
Vulnerabilidad local en kernel Linux (AV:L) sin interacción (UI:N) con privilegios (PR:L) que afecta integridad de cachés TLB; permite lectura/corrupción de memoria mediante page table walks incorrectos.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/0199c9d57861f17b556b6cba1f765c7cce79745b
- https://git.kernel.org/stable/c/47490bbb05c8c0e09cc3cfd237d8934ffc340583
- https://git.kernel.org/stable/c/48125cd9c55cbe297b59fd1f9bda48b0960bd181
- https://git.kernel.org/stable/c/8ca7284da0e67b3e71d90ec17f08286774245ad9
- https://git.kernel.org/stable/c/c2ff4764e03e7a8d758352f4aceb8fe1be6ac971
- https://git.kernel.org/stable/c/d766a49d9b55705c4737cd8bb5d3faa2d31330fd
- https://git.kernel.org/stable/c/dced308d7d6a0de1c09d2058f38f1aaaf5cbb914
- https://git.kernel.org/stable/c/fe93e907b1af03cc229a80aa64a570a103d2b279
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-63875",
"cveTags": [],
"metrics": {
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{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.8,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
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"impactScore": 5.9,
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}
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"defaultStatus": "affected"
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"published": "2026-07-19T16:17:04.357",
"references": [
{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
"url": "https://git.kernel.org/stable/c/fe93e907b1af03cc229a80aa64a570a103d2b279",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Awaiting Analysis",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: tlb: Flush walk cache when unsharing PMD tables\n\nWhen huge_pmd_unshare() is called to unshare a PMD table, the\ntlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true\nbut the aarch64 tlb_flush() only checked tlb->freed_tables to\ndetermine whether to use TLBF_NONE (vae1is, invalidates walk\ncache) or TLBF_NOWALKCACHE (vale1is, leaf-only).\n\nThis caused the stale PMD page table entry to remain in the walk cache\nafter unshare, potentially leading to incorrect page table walks.\n\nFix by including unshared_tables in the check, so that when\nunsharing tables, TLBF_NONE is used and the walk cache is properly\ninvalidated.\n\nHere is the detailed distinction between vae1is and vale1is:\n\n| Instruction Combination | Actual Invalidation Scope |\n| ------------------------ | --------------------------------------------------|\n| `VAE1IS` + TTL=`0` | All entries at all levels (full invalidation) |\n| `VAE1IS` + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2 |\n| `VALE1IS` + TTL=`0` | Leaf entries at all levels (non-leaf not cleared) |\n| `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only |"
}
],
"lastModified": "2026-07-27T17:44:23.777",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}